Optical investigation of ac preflashover of alumina ceramic in vacuum

Zhang, Guanjun; Zhao, Wen-Bin; Zhang, Yan; Liu, Yuan-Shing

doi:10.1109/tdei.2004.1306728

Cited by 7 publications

(1 citation statement)

References 14 publications

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“…Le Gressus et al proposed the electron triggered polarization relaxation (EPTR) model to describe the surface flashover phenomena, indicating the importance of inner charge transport [13]. Zhang et al proved that prior to the field emission, charge carriers could be injected into traps in surface layer through energy gap [14], especially when interfacial potential due to electrode contact is fine [15]. Recently, Song et al studied the accumulation of trapped charges under electron irradiation [16].…”

Section: Introductionmentioning

confidence: 99%

Estimation of surface flashover threshold in vacuum: from multipactor to discharge plasma

Sun¹,

Song²,

Guo³

et al. 2018

J. Phys. D: Appl. Phys.

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We propose a novel theoretical formula to estimate the surface flashover threshold in vacuum using the intrinsic properties of dielectric material as well as dielectric-vacuum configuration. The method is based on an above-surface model called secondary electron emission avalanche (SEEA), where flashover development can be divided into multipactor discharge, outgassing and an ionization avalanche which eventually leads to a plasma discharge. The transition from SEE-dominated regime to discharge plasma is supposed to be of significance where gas breakdown takes place within a nonuniform desorbed gas cloud in the vicinity of dielectric surface. Flashover occurs when specific space charge multiplication is achieved, yielding the critical pressure and breakdown voltage. The depiction of previous stages involves the secondary electron emission of dielectric materials, desorption and diffusion of adsorbed gas, ambient temperature, electrode structure, etc. Both particle-in-cell simulation and experiment data can corroborate the obtained theoretical results.

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Section: Introductionmentioning

confidence: 99%

Estimation of surface flashover threshold in vacuum: from multipactor to discharge plasma

Sun¹,

Song²,

Guo³

et al. 2018

J. Phys. D: Appl. Phys.

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Flashover strength improvement and multipactor suppression in vacuum using surface charge pre-conditioning on insulator

Sun

Guo

et al. 2018

Journal of Applied Physics

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Surface charging commonly appears on dielectrics in vacuum in the presence of electron bombardment, seriously aggravating the superficial withstand strength of assorted devices. Nonetheless, a pre-conditioning technique is introduced in this paper capitalizing on surface charges to play an opposite role, enhancing flashover strength and suppressing the multipactor which is frequently found over vacuum insulator. A theoretical study is first performed, incorporated with particle-in-cell simulation to show the critical condition for a single-surface multipactor to initiate. Therewith, it is proven that a negative charge accretion in cathode adjacency can prevent the multipactor from commencing with efficiency. Subsequently, an analytical model is constructed to expatiate multipactor expansion with pre-set surface charges getting involved, illustrating an upper bound of its propagation velocity, influenced by pre-conditioning. Corresponding experiments are also conducted to corroborate previous conclusions, presenting both a deflected electron trajectory and an improved flashover threshold. In the end, a brief discussion is given on a possible method to generate desired surface charge distribution in practical applications.

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Investigation on Surface Insulation Strength of Machinable Ceramic Material under Pulsed Voltage in Vacuum

Zhang

Zhao

et al. 2006

2006 International Symposium on Discharges and Electrical Insulation in Vacuum

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Optical investigation of ac preflashover of alumina ceramic in vacuum

Cited by 7 publications

References 14 publications

Estimation of surface flashover threshold in vacuum: from multipactor to discharge plasma

Estimation of surface flashover threshold in vacuum: from multipactor to discharge plasma

Flashover strength improvement and multipactor suppression in vacuum using surface charge pre-conditioning on insulator

Investigation on Surface Insulation Strength of Machinable Ceramic Material under Pulsed Voltage in Vacuum

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